Cable-type secondary battery

ABSTRACT

Provided is a cable-type secondary battery extending longitudinally including a lithium ion supplying core comprising an electrolyte, an inner electrode support of a hollow structure formed to surround an outer surface of the lithium ion supplying core, an inner electrode formed on a surface of the inner electrode support and including an inner current collector and an inner electrode active material, a separation layer formed to surround an outer surface of the inner electrode to prevent a short circuit between electrodes, and an outer electrode formed to surround an outer surface of the separation layer and including an outer electrode active material layer and an outer current collector.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. application Ser. No.14/257,228 filed Apr. 21, 2014, now U.S. Pat. No. 9,184,470, which is acontinuation of International Application No. PCT/KR2013/009121 filed onOct. 11, 2013, which claims priority to Korean Patent Application No.10-2012-0113161 filed in the Republic of Korea on Oct. 11, 2012 andKorean Patent Application No. 10-2013-0121487 filed in the Republic ofKorea on Oct. 11, 2013, the disclosures of which are incorporated hereinby reference.

TECHNICAL FIELD

The present disclosure relates to a cable-type secondary battery whichcan freely change in shape, and more particularly, to a cable-typesecondary battery including an inner electrode support of a hollowstructure receiving a lithium ion supplying core therein.

BACKGROUND ART

A secondary battery is a device that stores electrical energy inchemical form and converts the stored chemical energy into electricalenergy to generate electricity when needed. The secondary battery isalso referred to as a rechargeable battery because it can be rechargedrepeatedly. A common secondary battery includes a lead accumulator, aNiCd battery, a NiMH accumulator, a Li-ion battery, a Li-ion polymerbattery, and the like. When compared to a disposable primary battery,not only is the secondary battery more economically efficient, it isalso more environmentally friendly.

A secondary battery is currently used in applications requiring lowelectric power, for example, equipment to start a vehicle, a mobiledevice, a tool, an uninterruptible power supply, and the like. Recently,as the development of wireless communication technologies has beenleading to the popularization of mobile devices and even to themobilization of many kinds of conventional devices, the demand for asecondary battery has been dramatically increasing. A secondary batteryis also used in an environmentally friendly next-generation vehicle suchas a hybrid vehicle or an electric vehicle to reduce the cost and weightand to increase the service life of the vehicle.

Generally, most secondary batteries have a cylindrical, prismatic, orpouch shape. This is associated with a fabrication process of asecondary battery that mounts an electrode assembly composed of ananode, a cathode, and a separator in a cylindrical or prismatic metalcasing or a pouch-shaped casing of an aluminum laminate sheet, andinjects an electrolyte into the electrode assembly. Because apredetermined mounting space for the electrode assembly is necessary inthis process, the cylindrical, prismatic or pouch shape of the secondarybattery is a limitation in developing various shapes of mobile devices.Accordingly, there is a need for a new type of secondary battery that iseasily adaptable in shape.

To fulfill this need, suggestions have been made to develop a linearbattery having a very high ratio of length to cross-sectional diameter.Korean Patent Application publication No. 2005-99903 discloses anadaptable battery consisting of an inner electrode, an outer electrodeand an electrolyte layer interposed therebetween. However, such batteryhas poor flexibility. The linear battery uses a polymer electrolyte toform an electrolyte layer, but this causes difficulties in the inflow ofthe electrolyte into an electrode active material, thereby increasingthe resistance of the battery and deteriorating the capacity and cyclecharacteristics thereof.

DISCLOSURE Technical Problem

Therefore, it is an object of the present disclosure to provide asecondary battery having a new linear structure, which can easily changein shape, maintain excellent stability and performances as a secondarybattery, and facilitate the inflow of an electrolyte into an electrodeactive material.

Technical Solution

To achieve the above object, the present disclosure provides acable-type secondary battery extending longitudinally including alithium ion supplying core comprising an electrolyte, an inner electrodesupport of a hollow structure formed to surround an outer surface of thelithium ion supplying core, an inner electrode formed on a surface ofthe inner electrode support and including an inner current collector andan inner electrode active material layer, a separation layer formed tosurround an outer surface of the inner electrode to prevent a shortcircuit between electrodes, and an outer electrode formed to surround anouter surface of the separation layer and including an outer electrodeactive material layer and an outer current collector.

The inner electrode support of the hollow structure may be a hollowfiber.

The inner electrode support of the hollow structure may have a pore onthe surface to allow the electrolyte to move to an inner electrodeactive material and an outer electrode active material.

The pore may have a diameter in a range of 10 nm to 100 μm.

The hollow fiber may be formed from at least one selected from the groupconsisting of polyethylene, polypropylene, polytetrafluoroethylene,polyvinylidenefluoride, polyimide, polyethyleneterephthalate,polyamide-imide, polyesterimide, polyethersulfone, and polysulfone.

As the inner current collector, a wound wire-type current collector, awound sheet-type current collector, or a metal coating layer may beused.

The inner electrode may include the inner electrode active materiallayer formed to surround the outer surface of the inner electrodesupport and the inner current collector formed to surround the outersurface of the inner electrode active material layer, or the innerelectrode may include the inner current collector formed to surround theouter surface of the inner electrode support and the inner electrodeactive material layer formed to surround the outer surface of the innercurrent collector.

The outer electrode may include the outer electrode active materiallayer formed to surround the outer surface of the separation layer andthe outer current collector formed to surround the outer surface of theouter electrode active material layer, the outer electrode may includethe outer current collector formed to surround the outer surface of theseparation layer and the outer electrode active material layer formed tosurround the outer surface of the outer current collector, the outerelectrode may include the outer current collector formed to surround theouter surface of the separation layer and the outer electrode activematerial layer formed to surround the outer surface of the outer currentcollector and to come into contact with the separation layer, or theouter electrode may include the outer electrode active material layerformed to surround the outer surface of the separation layer and thewire-type outer current collector formed to be included inside the outerelectrode active material layer by being covered therein and to surroundthe outer surface of the separation layer with spacing apart therefrom.

Also, there is no special limitation on a shape of the outer currentcollector, but it is preferred to use a pipe-type current collector, awound wire-type current collector, a wound sheet-type current collector,or a mesh-type current collector.

The inner current collector is not limited to a specific type, but mayinclude an inner current collector made of stainless steel, aluminum,nickel, titanium, sintered carbon, or copper; stainless steel treatedwith carbon, nickel, titanium or silver on the surface thereof; analuminum-cadmium alloy; a non-conductive polymer treated with aconductive material on the surface thereof; or a conductive polymer.

As the conductive material, polyacetylene, polyaniline, polypyrrole,polythiophene, polysulfurnitride, indium tin oxide (ITO), silver,palladium, and nickel may be used, and the conductive polymer may be apolymer of any one compound selected from polyacetylene, polyaniline,polypyrrole, polythiophene, and polysulfurnitride, or mixtures thereof.

The outer current collector may be made of stainless steel, aluminum,nickel, titanium, sintered carbon, or copper; stainless steel treatedwith carbon, nickel, titanium or silver on the surface thereof; analuminum-cadmium alloy; a non-conductive polymer treated with aconductive material on the surface thereof; a conductive polymer; ametal paste comprising metal powders of Ni, Al, Au, Ag, Al, Pd/Ag, Cr,Ta, Cu, Ba or ITO; or a carbon paste comprising carbon powders ofgraphite, carbon black or carbon nanotube.

The lithium ion supplying core of the present disclosure comprises theelectrolyte, and the electrolyte is not limited to a specific type butmay use an electrolyte selected from a non-aqueous electrolyte solutionusing ethylene carbonate (EC), propylene carbonate (PC), butylenecarbonate (BC), vinylene carbonate (VC), diethyl carbonate (DEC),dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), methyl formate(MF), γ-butyrolactone (γ-BL), sulfolane, methyl acetate (MA) or methylpropionate (MP); and a gel-type polymer electrolyte using polyethyleneoxide (PEO), polyvinylidene fluoride (PVdF), polymethylmethacrylate(PMMA), polyacrylonitrile (PAN), or polyvinyl acetate (PVAc); or a solidelectrolyte using PEO, polypropylene oxide (PPO), polyethylene imine(PEI), polyethylene sulphide (PES), or polyvinyl acetate (PVAc). Also,the electrolyte may further comprise a lithium salt, and it is preferredto use, as the lithium salt, LiCl, LiBr, LiI, LiClO₄, LiBF₄, LiB₁₀Cl₁₀,LiPF₆, LiCF₃SO₃, LiCF₃CO₂, LiAsF₆, LiSbF₆, LiAlCl₄, CH₃SO₃Li, CF₃SO₃Li,(CF₃SO₂)₂NLi, lithium chloroborate, lower aliphatic lithium carbonate,and lithium tetraphenylborate.

The inner electrode of the present disclosure may be an anode or acathode, and the outer electrode may be a cathode or an anode, oppositeto the inner electrode.

Also, when the inner electrode is an anode and the outer electrode is acathode, the inner electrode active material layer may be an anodeactive material layer including particles of any one active materialselected from the group consisting of natural graphite, artificialgraphite, or a carbonaceous material; lithium-containing titaniumcomposite oxide (LTO; lithium titanium oxide), and metals (Me) includingSi, Sn, Li, Zn, Mg, Cd, Ce, Ni and Fe; alloys of the metals (Me); oxides(MeOx) of the metals (Me); and composites of the metals (Me) and carbon,or mixtures thereof, and the outer electrode active material layer maybe a cathode active material layer including particles of any one activematerial selected from the group consisting of LiCoO₂, LiNiO₂, LiMn₂O₄,LiCoPO₄, LiFePO₄, LiNiMnCoO₂, and LiNi_(1−x−y−z)Co_(x)M1_(y)M2_(z)O₂(wherein each of M1 and M2 is, independently, any one selected from thegroup consisting of Al, Ni, Co, Fe, Mn, V, Cr, Ti, W, Ta, Mg and Mo, andx, y and z are, independently, atomic fractions of elements in an oxidecomposition, in which 0≦x≦0.5, 0≦y≦0.5, 0≦z<0.5, and x+y+z≦1), ormixtures thereof.

Also, when the inner electrode is a cathode and the outer electrode isan anode, the inner electrode active material layer may be a cathodeactive material layer including particles of any one active materialselected from the group consisting of LiCoO₂, LiNiO₂, LiMn₂O₄, LiCoPO₄,LiFePO₄, LiNiMnCoO₂, and LiNi_(1−x−y−z), Co_(x)M1_(y)M2_(z)O₂ (whereineach of M1 and M2 is, independently, any one selected from the groupconsisting of Al, Ni, Co, Fe, Mn, V, Cr, Ti, W, Ta, Mg and Mo, and x, yand z are, independently, atomic fractions of elements in an oxidecomposition, in which 0≦x≦0.5, 0≦y<0.5, 0≦z<0.5, and x+y+z≦1), ormixtures thereof, and the outer electrode active material layer may bean anode active material layer including particles of any one activematerial selected from the group consisting of natural graphite,artificial graphite, or a carbonaceous material; lithium-containingtitanium composite oxide (LTO), and metals (Me) including Si, Sn, Li,Zn, Mg, Cd, Ce, Ni and Fe; alloys of the metals(Me); oxides (MeOx) ofthe metals (Me); and composites of the metals (Me) and carbon, ormixtures thereof, however the present disclosure is not limited thereto.

The separation layer of the present disclosure may use an electrolytelayer or a separator.

The electrolyte layer is not limited to a specific type, but it ispreferred to use a gel-type polymer electrolyte using PEO, PVdF, PMMA,PAN, or PVAc; or a solid electrolyte using PEO, polypropylene oxide(PPO), polyethylene imine (PEI), polyethylene sulphide (PES), orpolyvinyl acetate (PVAc). Also, the electrolyte layer may furthercomprise a lithium salt, and a non-limiting example of the lithium saltmay include LiCl, LiBr, LiI, LiClO₄, LiBF₄, LiB₁₀Cl₁₀, LiPF₆, LiCF₃SO₃,LiCF₃CO₂, LiAsF₆, LiSbF₆, LiAlCl₄, CH₃SO₃Li, CF₃SO₃Li, (CF₃SO₂)₂NLi,lithium chloroborate, lower aliphatic lithium carbonate, and lithiumtetraphenylborate.

When a separator is used as the separation layer, the cable-typesecondary battery of the present disclosure requires an electrolyte, andthe separator is not limited to a specific type, but may use a poroussubstrate made of a polyolefin-based polymer selected from the groupconsisting of ethylene homopolymers, propylene homopolymers,ethylene-butene copolymers, ethylene-hexene copolymers, andethylene-methacrylate copolymers; a porous substrate made of a polymerselected from the group consisting of polyesters, polyacetals,polyamides, polycarbonates, polyimides, polyether ether ketones,polyether sulfones, polyphenylene oxides, polyphenylene sulfides andpolyethylene naphthalenes; or a porous substrate made of a mixture ofinorganic particles and a binder polymer.

The cable-type secondary battery may further include an electrolyteabsorption layer between the inner electrode and the separation layer.

Also, the cable-type secondary battery may further include a firstelectrolyte absorption layer between the inner electrode and theseparation layer, and a second electrolyte absorption layer between theseparation layer and the outer electrode.

The wire-type current collector may have a structure of at least twowires that are spirally twisted around each other.

The cable-type secondary battery may have a cross section of a circularor polygonal shape.

Also, the present disclosure provides a cable-type secondary batteryincluding a plurality of inner electrodes, and also provides acable-type secondary battery including a plurality of inner electrodeshaving separation layers.

Advantageous Effects

In accordance with the present disclosure, a lithium ion supplying corecomprising an electrolyte is disposed within an inner electrode support,and the inner electrode support has a hollow structure, so theelectrolyte of the lithium ion supplying core can be easily penetratedinto an electrode active material, thereby facilitating the supply andexchange of lithium ions. Accordingly, the cable-type secondary batteryof the present disclosure has such a lithium ion supplying core toexhibit superior capacity and cycle characteristics of the battery.Also, the cable-type secondary battery of the present disclosure mayfurther improve flexibility due to having the inner electrode support ofthe hollow structure.

DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate preferred embodiments of thepresent disclosure and, together with the foregoing disclosure, serve toprovide further understanding of the technical spirit of the presentdisclosure. However, the present disclosure is not to be construed asbeing limited to the drawings.

FIG. 1 is a view illustrating a cable-type secondary battery accordingto an exemplary embodiment of the present disclosure.

FIG. 2 is a view illustrating a cable-type secondary battery accordingto an exemplary embodiment of the present disclosure.

FIG. 3 is a view illustrating a cable-type secondary battery accordingto an exemplary embodiment of the present disclosure.

FIG. 4 is a perspective view schematically illustrating a spiralelectrode provided in a cable-type secondary battery according to anexemplary embodiment of the present disclosure.

FIG. 5 is a cross sectional view of FIG. 4.

FIG. 6 is a cross sectional view illustrating a cable-type secondarybattery having a plurality of inner electrodes according to an exemplaryembodiment of the present disclosure.

FIG. 7 is a cross sectional view illustrating a cable-type secondarybattery having a plurality of inner electrodes according to an exemplaryembodiment of the present disclosure.

FIG. 8 is a cross sectional view illustrating a cable-type secondarybattery having a plurality of inner electrodes according to an exemplaryembodiment of the present disclosure.

MODE FOR DISCLOSURE

Hereinafter, the present disclosure will be described in detail withreference to the accompanying drawings. Prior to the description, itshould be understood that the terms used in the specification and theappended claims should not be construed as limited to general anddictionary meanings, but interpreted based on the meanings and conceptscorresponding to technical aspects of the present disclosure on thebasis of the principle that the inventor is allowed to define termsappropriately for the best explanation.

In FIG. 1, an example of a cable-type secondary battery according to thepresent disclosure is schematically illustrated. However, theconfigurations illustrated in the drawings and the embodiments are justpreferable examples for the purpose of illustrations only, not intendedto limit the scope of the disclosure, so it should be understood thatother equivalents and modifications could be made thereto withoutdeparting from the spirit and scope of the disclosure.

The cable-type secondary battery 100 of the present disclosure thatextends longitudinally includes a lithium ion supplying core 110comprising an electrolyte; an inner electrode support 120 of a hollowstructure formed to surround the outer surface of the lithium ionsupplying core 110 and an inner electrode 130 formed on the surface ofthe inner electrode support 120 and including an inner electrode activematerial layer and an inner current collector; a separation layer 140formed to surround the outer surface of the inner electrode to prevent ashort circuit between electrodes; and an outer electrode 150 formed tosurround the outer surface of the separation layer 140 and including anouter electrode active material layer and an outer current collector.

In this instance, the inner electrode support of the hollow structuremay employ any type if it has a hollow structure capable of receivingthe electrolyte of the lithium ion supplying core 110 and has a poreformed on the surface to allow the electrolyte to freely move to theinner electrode active material and the outer electrode active materialto ensure a wetting performance.

The inner electrode support of the hollow structure may include, forexample, but is not limited to, a hollow fiber.

The hollow fiber may be obtained by a conventional method of forming ahollow fiber, using at least one polymer selected from the groupconsisting of polyethylene, polypropylene, polytetrafluoroethylene,polyvinylidenefluoride, polyimide, polyethyleneterephthalate,polyamide-imide, polyesterimide, polyethersulfone, and polysulfone.

The inner electrode support may have a diameter in a range of 0.5 to 10mm, and may have a pore of a diameter in a range of 10 nm to 100 μm onthe surface thereof.

Also, a cross section of the cable-type secondary battery according toan exemplary embodiment of the present disclosure is not limited to aparticular shape, and may have any shape that does not damage the natureof the present disclosure. For example, the cross section of thecable-type secondary battery may have a circular shape or a polygonalshape, and the circular shape may correspond to a circular structure ofgeometrically perfect symmetry and an asymmetrical oval structure. Thepolygonal shape is not limited to a particular structure unless suchstructure is in a shape of a two-dimensional sheet, and the polygonalstructure may be, as a non-limiting example, a triangle, a square, apentagon, or a hexagon.

The cable-type secondary battery of the present disclosure has ahorizontal cross section of the exemplary shape described in theforegoing, and has a linear structure elongating in a longitudinaldirection with regard to the horizontal cross section as well asflexibility, so it can freely change in shape.

Conventional cable-type secondary batteries have an electrolyte layerinterposed between an inner electrode and an outer electrode. In orderfor the electrolyte layer to isolate the inner electrode from the outerelectrode to prevent a short circuit, the electrolyte layer is requiredto be made of a gel-type polymer electrolyte or a solid polymerelectrolyte having a certain degree of mechanical properties. However,such a gel-type polymer electrolyte or solid polymer electrolyte failsto provide superior performances as a source for lithium ions, so theelectrolyte layer should have an increased thickness so as tosufficiently provide lithium ions to an electrode active material layer.Such a thickness increase in the electrolyte layer widens an intervalbetween the electrodes to cause resistance increase, therebydeteriorating battery performances.

In contrast, the cable-type secondary battery 100 of the presentdisclosure has the lithium ion supplying core 110 comprising theelectrolyte, the inner electrode support of the present disclosure has ahollow structure, and the inner current collector of an open structureand the inner electrode active material layer are applied to the innerelectrode, so that the electrolyte of the lithium ion supplying core 110can pass through the inner electrode support to reach the inner currentcollector, the inner electrode active material layer 130 and the outerelectrode active material layer.

Here, the open structure refers to a structure in which the openstructure serves as a boundary surface through which a substance may betransferred freely from the inside of the structure to the outsidethereof

Accordingly, it is not necessary to excessively increase the thicknessof an electrolyte layer. Also, an electrolyte layer may not be adoptedas an essential component, and therefore, only a separator may beoptionally used. That is, since the cable-type secondary batteryaccording to an exemplary embodiment of the present disclosure has alithium ion supplying core 110 comprising the electrolyte, it mayfacilitate the penetration into an electrode active material, andeventually facilitate the supply and exchange of lithium ions inelectrodes, thereby exhibiting superior capacity and cyclecharacteristics of the battery.

The lithium ion supplying core 110 comprises the electrolyte, and theelectrolyte is not limited to a specific type, but may use a non-aqueouselectrolyte solution using ethylene carbonate (EC), propylene carbonate(PC), butylene carbonate (BC), vinylene carbonate (VC), diethylcarbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC),methyl formate (MF), γ-butyrolactone (γ-BL), sulfolane, methyl acetate(MA), or methyl propionate (MP); a gel-type polymer electrolyte usingPEO, PVdF, PMMA, PAN, or PVAc; or a solid electrolyte using PEO,polypropylene oxide (PPO), polyethylene imine (PEI), polyethylenesulphide (PES), or polyvinyl acetate (PVAc). Also, the electrolyte mayfurther comprise a lithium salt, and preferred examples of the lithiumsalt include LiCl, LiBr, LiI, LiClO₄, LiBF₄, LiB₁₀Cl₁₀, LiPF₆, LiCF₃SO₃,LiCF₃CO₂, LiAsF₆, LiSbF₆, LiAlCl₄, CH₃SO₃Li, CF₃SO₃Li, (CF₃SO₂)₂NLi,lithium chloroborate, lower aliphatic lithium carbonate, lithiumtetraphenylborate, and the like. Also, the lithium ion supplying core110 may consist of only an electrolyte, and in the case of a liquidelectrolyte, a porous carrier may be used together.

The inner electrode 130 of the present disclosure may include the innerelectrode active material layer formed to surround the outer surface ofthe inner electrode support and the inner current collector formed tosurround the outer surface of the inner electrode active material layer,or may include the inner current collector formed to surround the outersurface of the inner electrode support and the inner electrode activematerial layer formed to surround the outer surface of the inner currentcollector. The inner current collector may use, as a non-limitingexample, a wound wire-type current collector, a wound sheet-type currentcollector, or a metal coating layer.

Specifically, in the inner electrode according to an exemplaryembodiment of the present disclosure, the inner current collector may beformed on the inner electrode support of the hollow structure, andsubsequently, the inner electrode active material layer may be formed onthe surface of the inner current collector. In this instance, the innerelectrode active material layer may be formed to surround the outersurface of the inner current collector such that the open structure ofthe inner current collector may not be exposed through the outer surfaceof the inner electrode active material layer, and the inner electrodeactive material layer may be formed on the surface of the open structureof the inner current collector such that the open structure of the innercurrent collector may be exposed through the outer surface of the innerelectrode active material layer. For example, a case in which an activematerial layer is formed on a surface of a wound wire-type currentcollector, and a case in which a wire-type current collector having anelectrode active material layer formed thereon is wound and used may becontemplated.

Also, in the inner electrode according to an exemplary embodiment of thepresent disclosure, the inner electrode active material layer may befirst formed on the inner electrode support of the hollow structure, andsubsequently, the inner current collector may be formed on the surfaceof the inner electrode active material layer. In this case, the innerelectrode active material layer and the inner current collector may beformed to implement an inner electrode of an open structure such thatpores of the inner electrode of the hollow structure are not blocked. Inthis instance, when a metal coating layer is applied as the innercurrent collector, for example, an electroplating method may be used.

The inner current collector may be manufactured using stainless steel,aluminum, nickel, titanium, sintered carbon, copper, stainless steeltreated with carbon, nickel, titanium or silver on the surface thereof,an aluminum-cadmium alloy, a non-conductive polymer treated with aconductive material on the surface thereof, or a conductive polymer.

A current collector serves to collect electrons generated by anelectrochemical reaction of an active material or to supply electronsrequired for an electrochemical reaction. In general, a metal such ascopper or aluminum is used. Especially, a current collector using anon-conductive polymer treated with a conductive material on the surfacethereof or a conductive material comprising a conductive polymer has arelatively better flexibility than a current collector using a metalsuch as copper or aluminum. Also, a lightweight battery may be achievedby replacing a metal current collector with a polymer current collector.

The conductive material may include polyacetylene, polyaniline,polypyrrole, polythiophene, polysulfurnitride, indium tin oxide (ITO),silver, palladium, nickel, and the like. The conductive polymer mayinclude polyacetylene, polyaniline, polypyrrole, polythiophene,polysulfurnitride, and the like. However, the non-conductive polymerused for the current collector is not limited to a specific type.

The outer current collector of the present disclosure is not limited toa specific type, but may use a pipe-type current collector, a woundwire-type current collector, a wound sheet-type current collector, or amesh-type current collector. Also, the outer current collector may bemanufactured using stainless steel, aluminum, nickel, titanium, sinteredcarbon, or copper; stainless steel treated with carbon, nickel, titaniumor silver on the surface thereof; an aluminum-cadmium alloy; anon-conductive polymer treated with a conductive material on the surfacethereof; a conductive polymer; a metal paste comprising metal powders ofNi, Al, Au, Ag, Pd/Ag, Cr, Ta, Cu, Ba or ITO; or a carbon pastecomprising carbon powders of graphite, carbon black or carbon nanotube.

The inner electrode may be an anode or a cathode, and the outerelectrode may be a cathode or an anode, opposite to the inner electrode.

The electrode active material layer of the present disclosure allowsions to move through the current collector, and the movement of the ionsis caused by the interaction through intercalation/deintercalation ofthe ions into and from the electrolyte layer.

The electrode active material layer may be classified into an anodeactive material layer and a cathode active material layer.

Specifically, when the inner electrode is an anode and the outerelectrode is a cathode, the inner electrode active material layer is ananode active material layer and may include particles of any one activematerial selected from the group consisting of natural graphite,artificial graphite, or carbonaceous materials; lithium-containingtitanium composite oxide (LTO; lithium titanium oxide), and metals (Me)such as Si, Sn, Li, Zn, Mg, Cd, Ce, Ni, or Fe; alloys consisted of themetals (Me); oxides (MeOx) of the metals (Me); and composites of themetals (Me) and carbon, or mixtures thereof, and the outer electrodeactive material layer is a cathode active material layer and may includeparticles of any one active material selected from the group consistingof LiCoO₂, LiNiO₂, LiMn₂O₄, LiCoPO₄, LiFePO₄, LiNiMnCoO₂, andLiNi_(1−x−y−z)Co_(x)M1_(y)M2_(z)O₂ (wherein each of M1 and M2 is,independently, any one selected from the group consisting of Al, Ni, Co,Fe, Mn, V, Cr, Ti, W, Ta, Mg, and Mo, and x, y, and z are,independently, atomic fractions of elements in an oxide composition, inwhich 0≦x<0.5, 0≦y≦0.5, 0≦z≦0.5, and x+y+z≦1), or mixtures thereof.

Also, when the inner electrode is a cathode and the outer electrode isan anode, the inner electrode active material layer may be a cathodeactive material layer and the outer electrode active material layer maybe an anode active material layer.

As described in the foregoing, the outer electrode may include the outerelectrode 150 formed to surround the outer surface of the separationlayer 140, and including the outer electrode active material layer andthe outer current collector, as shown in FIG. 1.

In this instance, the outer electrode 150 may be variously implementedbased on the placement of the outer electrode active material layer andthe outer current collector in contact with the separation layer.

For example, the outer electrode 150 may have a structure including theouter electrode active material layer formed to surround the outersurface of the separation layer 140 and the outer current collectorformed to surround the outer surface of the outer electrode activematerial layer, a structure including the outer current collector formedto surround the outer surface of the separation layer and the outerelectrode active material layer formed to surround the outer surface ofthe outer current collector, a structure including the outer currentcollector formed to surround the outer surface of the separation layerand the outer electrode active material layer formed to surround theouter surface of the outer current collector and to come into contactwith the separation layer, or a structure including the outer electrodeactive material layer formed to surround the outer surface of theseparation layer and the wire-type outer current collector formed to beincluded inside the outer electrode active material layer by beingcovered therein and to surround the outer surface of the separationlayer with spacing apart therefrom.

In this instance, when the outer current collector is wound on the outersurface of the separation layer, a contact area with the active materiallayer sufficiently increases to ensure a certain degree of batteryperformances. Particularly, since the outer electrode active materiallayer according to an exemplary embodiment of the present disclosure isformed by coating an active material, for example, in the form of aslurry on the outer surface of the outer current collector, the outerelectrode active material layer may come into contact with theseparation layer. Also, the outer current collector may be includedinside the outer electrode active material layer by being coveredtherein, while surrounding the outer surface of the separation layerwith spacing apart therefrom by the outer electrode active materiallayer. As a result, an electric contact between the outer currentcollector and the outer electrode active material layer may be improved,thereby contributing to the enhancement of battery characteristics.

For example, when a wound wire-type outer current collector havingflexibility is used as the outer current collector, the wound wire-typeouter current collector has elasticity due to its shape and serves toenhance the overall flexibility of the cable-type secondary battery.Also, when excessive external force is applied to the cable-typesecondary battery of the present disclosure, the wire-type outer currentcollector of the present disclosure undergoes very little excessivedeformation such as crumpling or bending due to its shapecharacteristics, so concerns about a short circuit caused by a contactwith the inner current collector may be reduced.

The electrode active material layer includes an electrode activematerial, a binder and a conductive material, and combines with thecurrent collector to form the electrode. When the electrode is deformedby bending or severely folding due to external force, the electrodeactive material may be released. The release of the electrode activematerial results in performance deterioration and capacity reduction ofthe battery. However, the wound wire-type outer current collector havingelasticity functions to disperse the applied force when such adeformation occurs by the external force, from which the active materiallayer is less deformed, thereby preventing the release of the activematerial. The separation layer of the present disclosure may use anelectrolyte layer or a separator.

The electrolyte layer serving as an ion channel may use a gel-typepolymer electrolyte using PEO, PVdF, PMMA, PAN or PVAc, or a solidelectrolyte using PEO, polypropylene oxide (PPO), polyethylene imine(PEI), polyethylene sulphide (PES) or polyvinyl acetate (PVAc). Thematrix of the solid electrolyte preferably comprises a polymer or aceramic glass as the backbone. In a case of typical polymerelectrolytes, ions move very slowly in terms of a reaction rate, evenwhen the ionic conductivity is satisfied. Thus, the gel-type polymerelectrolyte which facilitates the movement of ions is preferably usedcompared to the solid electrolyte. The gel-type polymer electrolyte haspoor mechanical properties and thus may comprise a porous support or across-linked polymer to improve the poor mechanical properties. Theelectrolyte layer of the present disclosure can serve as a separator,and thus the use of a separate separator may be omitted.

The electrolyte layer of the present disclosure may further comprise thelithium salt. The lithium salt can improve the ionic conductivity andreaction rate, and may use, as a non-limiting example, LiCl, LiBr, LiI,LiClO₄, LiBF₄, LiB₁₀Cl₁₀, LiPF₆, LiCF₃SO₃, LiCF₃CO₂, LiAsF₆, LiSbF₆,LiAlCl₄, CH₃SO₃Li, CF₃SO₃Li, (CF₃SO₂)₂NLi, lithium chloroborate, loweraliphatic lithium carbonate, and lithium tetraphenylborate.

The separator is not limited to a specific type, but may use a poroussubstrate made of a polyolefin-based polymer selected from the groupconsisting of ethylene homopolymers, propylene homopolymers,ethylene-butene copolymers, ethylene-hexene copolymers, andethylene-methacrylate copolymers; a porous substrate made of a polymerselected from the group consisting of polyesters, polyacetals,polyamides, polycarbonates, polyimides, polyether ether ketones,polyether sulfones, polyphenylene oxides, polyphenylene sulfides andpolyethylene naphthalenes; or a porous substrate made of a mixture ofinorganic particles and a binder polymer. Particularly, in order for thelithium ions from the lithium ion supplying core to be easilytransferred to the outer electrode, it is preferred to use a non-wovenfabric separator corresponding to a porous substrate made of a polymerselected from the group consisting of polyesters, polyacetals,polyamides, polycarbonates, polyimides, polyether ether ketones,polyether sulfones, polyphenylene oxides, polyphenylene sulfides andpolyethylene naphthalenes.

The present disclosure has a protection coating, and the protectioncoating corresponds to an insulator and is formed on the outer surfaceof the outer current collector to protect the electrodes againstmoisture in the air and external impacts. The protection coating may bemade of a conventional polymer resin, for example, PVC, HDPE, or anepoxy resin.

Hereinafter, a cable-type secondary battery according to an exemplaryembodiment and a manufacturing method thereof will be briefly explainedwith reference to FIG. 1.

The cable-type secondary battery 100 according to an exemplaryembodiment of the present disclosure includes the lithium ion supplyingcore 110 comprising the electrolyte; the inner electrode support 120 ofthe hollow structure formed to surround the outer surface of the lithiumion supplying core 110 and the inner electrode 130 formed on the surfaceof the inner electrode support 120 and including the inner currentcollector and the inner electrode active material; the separation layer140 formed to surround the outer surface of the inner electrode toprevent a short circuit between electrodes; and the outer electrode 150formed to surround the outer surface of the separation layer 140 andincluding the outer electrode active material layer and the outercurrent collector.

First, the lithium ion supplying core 110 may be prepared by shaping apolymer electrolyte in a form of a wire using an extruder or the like.Also, the lithium ion supplying core 110 may be formed by providing aninner electrode support of a hollow structure and injecting anon-aqueous electrolyte solution into the center of the inner electrodesupport, or may be formed by providing a battery assembly having aprotection coating and injecting a non-aqueous electrolyte solution intothe center of an inner electrode support of a battery. Alternatively,the lithium ion supplying core 110 may be prepared by providing awire-type carrier made of a sponge material and injecting a non-aqueouselectrolyte solution therein.

Subsequently, an inner electrode is provided on the inner electrodesupport, and in this instance, the inner electrode is shaped asdescribed in the foregoing and may be provided by forming an innerelectrode active material layer to surround the outer surface of theinner electrode support and forming an inner current collector on theouter surface of the inner electrode active material layer, or may beprovided by forming an inner current collector on the outer surface ofthe inner electrode support and forming an inner electrode activematerial layer on the outer surface of the inner current collector.

For example, first, a linear wire-type or sheet-type inner currentcollector is prepared and wound on the inner electrode support 120. Aninner electrode active material layer is formed on the surface of thewound inner current collector by coating. As a coating method, a typicalcoating method may be applied, and specifically, an electroplatingmethod or an anodic oxidation process may be used. Preferably, tomaintain a regular interval, an electrode slurry containing an activematerial may be discontinuously applied by an extrusion-coating methodusing an extruder. In addition, an electrode slurry containing an activematerial may be applied by a dip coating method or an extrusion-coatingmethod using an extruder. In this instance, as the inner currentcollector, a metal coating layer may be introduced, and the metalcoating layer may be formed by an electroplating method.

Alternatively, an inner electrode active material layer may be firstformed on the surface of the inner electrode support, and various typesof inner current collectors may be introduced thereon.

Subsequently, the separation layer 140 comprising a polymer electrolytelayer is formed to surround the inner electrode 130. There is no speciallimitation on a method of forming the separation layer 140 comprisingthe electrolyte layer, but the use of an extrusion-coating method mayease the manufacture due to the characteristics of the cable-typesecondary battery having a linear shape.

An outer electrode is formed on the outer surface of the separationlayer 140, that is, the coated electrolyte, and the outer electrode mayhave various structures based on the placement of the outer electrodeactive material layer and the outer current collector as described inthe foregoing.

For example, the outer electrode 150 is formed by forming an activematerial layer on the outer surface of the separation layer 140 bycoating, and preparing an outer current collector and introducing ontothe outer surface of the outer electrode active material layer.

In this instance, the coating method of the inner electrode activematerial layer may be equally applied to coating for the outer electrodeactive material layer.

In this instance, as the outer current collector, a wound wire-typecurrent collector, a wound sheet-type current collector, a pipe-typecurrent collector, or a mesh-type current collector may be applied.

In this instance, the outer electrode may be formed by pre-forming theouter electrode active material layer on the outer current collector andapplying this onto the separation layer. For example, in a case of awound sheet-type current collector, an outer electrode active materiallayer may be formed on a sheet-type current collector and cut intopredetermined widths to prepare a sheet-type outer electrode.Subsequently, the sheet-type outer electrode in which the outerelectrode active material layer is prepared to come in contact with theseparation layer may be wound on the outer surface of the separationlayer so that the outer electrode may be formed on the separation layer.

Meanwhile, when the outer electrode has a structure of including anouter current collector formed to surround the outer surface of theseparation layer and an outer electrode active material layer formed tosurround the outer surface of the outer current collector and come intocontact with the separation layer, first, for example, a wire-type or asheet-type outer current collector is wound on the outer surface of theseparation layer. There is no special limitation on a winding method,however, for example, a wire-type outer current collector may be woundon the outer surface of the separation layer using a winding machine.Also, the outer electrode active material layer may be formed on theouter surface of the wound wire-type or sheet-type outer currentcollector by coating. The outer electrode active material layer may beformed to come into contact with the separation layer while surroundingthe wound wire-type current collector.

Also, when the outer electrode has a structure of including the outerelectrode active material layer formed to surround the outer surface ofthe separation layer and the outer current collector formed to beincluded inside the outer electrode active material layer by beingcovered therein and to surround the outer surface of the separationlayer with spacing apart therefrom, first of all, a portion of the outerelectrode active material layer intended to obtain in the end may befirst formed on the outer surface of the separation layer, an outercurrent collector may be formed thereon to surround the outer surface ofthe portion of the outer electrode active material layer and anadditional outer electrode active material layer may be formed on theouter current collector again to completely coat the outer currentcollector. In this instance, because the outer current collector isincluded inside the outer electrode active material layer with spacingapart from the separation layer, an electric contact between the currentcollector and the active material may be improved, thereby contributingto the enhancement of battery characteristics.

Finally, the protection coating 160 is formed to surround the outersurface of the electrode assembly. The protection coating 160corresponds to an insulator and is formed on the outermost surface toprotect the electrodes against moisture in the air and external impacts.As the protection coating 160, a conventional polymer resin may be used,and, for example, PVC, HDPE, or an epoxy resin may be used.

The cable-type secondary battery according to an exemplary embodiment ofthe present disclosure may further include an electrolyte absorptionlayer between the inner electrode and the separation layer.

Referring to FIG. 2, an inner electrode 230 of the present disclosure isprovided by forming an inner electrode active material layer and aninner current collector on the surface of an inner electrode support 220of a hollow structure in a sequential order or vice versa to maintain anopen structure, and forming an electrolyte absorption layer 270 on thesurface of the inner electrode 220 again, and the electrolyte absorptionlayer 270 can contain an electrolyte of a lithium ion supplying core 210and also include a lithium salt, which may facilitate the supply andexchange of lithium ions in electrodes, thereby contributing to theenhancement of battery capacity and cycle characteristics. Theprotection coating 260 may be formed to surround the outer surface of anouter electrode 250.

The electrolyte absorption layer is not limited to a specific type, butmay use an electrolyte absorption layer made of a polymer selected froma gel-type polymer electrolyte using PEO, PVdF, PVdF-HFP, PMMA, PAN, orPVAC; and a solid electrolyte using PEO, polypropylene oxide (PPO),polyethylene imine (PEI), polyethylene sulphide (PES), or polyvinylacetate (PVAc), and this electrolyte absorption layer may furtherinclude a lithium salt.

As a method of forming the electrolyte absorption layer, a dip coatingmethod or an extrusion-coating method using an extruder may be used.

Also, the cable-type secondary battery according to an exemplaryembodiment of the present disclosure may further include a firstelectrolyte absorption layer between the inner electrode and theseparation layer, and a second electrolyte absorption layer between theseparation layer and the outer electrode.

That is, referring to FIG. 3, a cable-type secondary battery 300includes a lithium ion supplying core 310 comprising an electrolyte; aninner electrode support 320 formed to surround the outer surface of thelithium ion supplying core, an inner electrode 330 including an innerelectrode active material layer and an inner current collector formed onthe surface of the inner electrode support in a sequential order or viceversa, and a first electrolyte absorption layer 370 formed on the outersurface of the inner electrode; a separation layer 340 formed tosurround the outer surface of the first electrolyte absorption layer toprevent a short circuit between electrodes; a second electrolyteabsorption layer 380 formed on the surface of the separation layer; andan outer electrode 350 formed to surround the outer surface of thesecond electrolyte absorption layer and including an outer electrodeactive material layer and an outer current collector having variousarrangements as described in the foregoing. The protection coating 360may be formed to surround the outer surface of the outer electrode 350.

In this instance, the first electrolyte absorption layer and the secondelectrolyte absorption layer may be each independently formed using thesame material and method as those of the electrolyte absorption layerdescribed in the foregoing.

Accordingly, the cable-type secondary battery according to an exemplaryembodiment of the present disclosure includes the electrolyte absorptionlayer on the outer surface of the inner electrode, or includes the firstand second electrolyte absorption layers respectively on the outersurfaces of the inner electrode and the separation layer, and thus, theelectrolyte of the lithium ion supplying core can be contained in theelectrolyte absorption layer, thereby improving the supply and exchangeof lithium ions in electrodes more effectively.

Also, in the cable-type secondary battery according to an exemplaryembodiment of the present disclosure, at least one of the innerelectrode and the outer electrode may correspond to a spiral electrodein which at least two wires are spirally twisted around each other.

Referring to FIGS. 4 and 5, a spiral electrode 20 may include at leasttwo wire-type current collectors 21 that are arranged in parallel toeach other and spirally twisted, and the spiral electrode 20 may have anelectrode active material layer 23 formed on the surface of a wire-typecurrent collector 22 by coating.

The spiral electrode 20 includes a plurality of strands of wire-typecurrent collectors 21 twisted spirally, and there is no speciallimitation on a twisted pattern, however the plurality of strands ofwire-type current collectors 21 may be twisted together after beingplaced in parallel to each other, or the plurality of strands ofwire-type current collectors 21 may be braided cross a strand overanother, similar to braided hair.

Particularly, when the inner electrode corresponds to an anode, a highcapacity anode material, for example, Si- or Sn-based metals or metalcompounds, used as an anode active material implements electrochemicalproperties through an alloying/dealloying process of Li ions due to itsmaterial properties. From this, a large volume change may occur due toexpansion, and if it becomes severe, the structure may collapse. As aresult, an electronic contact between metal active materials fails,thereby inhibiting the transfer of Li ions into the metal layer of theanode active material to cause cycle deterioration. Also, if the anodeactive material layer has a high density of metals and is thick, it isdifficult for Li ions to be diffused into the anode active materialmetal layer, thereby failing to provide sufficient capacity and goodrate characteristics. However, since the spiral electrode is such thatthe plurality of wire-type anode current collectors coated with theanode active material layer on the surface are twisted around eachother, a surface area which brings into reaction with Li ions during acharging and discharging process increases, thereby improving thebattery performance. Also, the rate characteristics of the battery maybe improved using a wire-type anode current collector having a thincoating of an anode active material layer. Further, a space presentbetween the plurality of strands of wire-type anode current collectorsin the spiral electrode can relieve stress or pressure applied in thebattery during charging and discharging, e.g., the volume expansion ofactive material layers, to prevent the deformation of the battery andensure the stability thereof, thereby increasing the life span of thebattery.

The spiral electrode may have a twist rate in a range of 0.01 to 10mm/turn. Here, the twist rate is a result of dividing a length of thespiral electrode by a number of twists, and the smaller value, thehigher extent of twisting. In this instance, when the twist rate exceeds10 mm/turn, a contact area between the wire-type current collectors istoo small and an effect of increasing a surface area is insignificant,and when the twist rate is less than 0.01 mm/turn, an extent of twistingis excessively high and there is a concern about electrode damages suchas peel-off of the electrode active material layer and disconnection ofthe current collector.

Hereinafter, another exemplary embodiment of the present disclosure willbe described with reference to FIGS. 6 through 8.

Referring to FIG. 6, a cable-type secondary battery 400 according to anexemplary embodiment of the present disclosure includes at least twolithium ion supplying cores 410 comprising an electrolyte; an innerelectrode support 420 of a hollow structure formed to surround the outersurface of each of the lithium ion supplying cores 410 and at least twoinner electrodes 430 formed on the surface of the inner electrodesupport 420 and arranged in parallel to one another, each including aninner electrode active material layer and an inner current collector; aseparation layer 440 formed to surround the outer surfaces of the innerelectrodes all together to prevent a short circuit between electrodes;and an outer electrode 450 formed to surround the outer surface of theseparation layer 440 and including an outer electrode active materiallayer and an outer current collector. Because of having the innerelectrode comprising the plurality of electrodes, the cable-typesecondary battery 400 may ease the balancing between an anode and acathode and prevent a possibility of a short circuit in the presence ofthe plurality of electrodes. The protection coating 460 may be formed tosurround the outer surface of the outer electrode 450.

Also, a cable-type secondary battery extending longitudinally accordingto an exemplary embodiment of the present disclosure includes at leasttwo lithium ion supplying cores comprising an electrolyte; an innerelectrode support of a hollow structure formed to surround the outersurface of each of the lithium ion supplying cores; at least two innerelectrode-separation layer assemblies formed on the surface of the innerelectrode support and arranged in parallel to one another, eachincluding an inner electrode consisting of an inner current collectorand an inner electrode active material layer and a separation layerformed to surround the outer surface of the inner electrode; and anouter electrode formed to surround the outer surfaces of the innerelectrode-separation layer assemblies all together and including anouter electrode active material layer and an outer current collector.

Similarly, the cable-type secondary battery including the innerelectrode comprising the plurality of electrodes may further include anelectrolyte absorption layer between the inner electrode and theseparation layer, or may include a first electrolyte absorption layerbetween the inner electrode and the separation layer and a secondelectrolyte absorption layer between the separation layer and the outerelectrode, as described in the foregoing.

Referring to FIG. 7, a cable-type secondary battery 500 according to anexemplary embodiment of the present disclosure includes at least twolithium ion supplying cores 510 comprising an electrolyte; an innerelectrode support 520 of a hollow structure formed to surround the outersurface of each of the lithium ion supplying cores; at least two innerelectrodes 530 formed on the surface of the inner electrode support 520and arranged in parallel to one another, each including an innerelectrode active material layer and an inner current collector; anelectrolyte absorption layer 570 formed on the outer surface of theinner electrode; a separation layer 540 formed to surround the outersurface of the electrolyte absorption layer to prevent a short circuitbetween electrodes; and an outer electrode 550 including an outerelectrode active material layer 551 and an outer current collector 552formed to surround the inner electrodes having the separation layers alltogether. The protection coating 560 may be formed to surround the outersurface of the outer electrode 550.

Also, referring to FIG. 8, a cable-type secondary battery 600 accordingto an exemplary embodiment of the present disclosure includes at leasttwo lithium ion supplying cores 610 comprising an electrolyte; an innerelectrode support 620 of a hollow structure formed to surround the outersurface of each of the lithium ion supplying cores 610; at least twoinner electrodes 630 formed on the surface of the inner electrodesupport 620 and arranged in parallel to one another, each including aninner electrode active material layer and an inner current collector; afirst electrolyte absorption layer 670 formed on the outer surface ofthe inner electrode; a separation layer 640 formed to surround the outersurface of the electrolyte absorption layer to prevent a short circuitbetween electrodes; a second electrolyte absorption layer 680 formed onthe outer surface of the separation layer; and an outer electrode 650including an outer electrode active material layer 651 and an outercurrent collector 652 formed to surround the inner electrodes having thesecond electrolyte absorption layers all together. The protectioncoating 660 may be formed to surround the outer surface of the outerelectrode 650.

Also, various modifications may be made to the cable-type secondarybattery including at least two inner electrodes according to anexemplary embodiment of the present disclosure.

For example, the cable-type secondary battery includes at least twolithium ion supplying cores comprising an electrolyte; an innerelectrode support of a hollow structure formed to surround the outersurface of each of the lithium ion supplying cores; at least two innerelectrodes formed on the surface of the inner electrode support andarranged in parallel to one another, each including an inner electrodeactive material layer and an inner current collector; an electrolyteabsorption layer formed on the outer surface of the inner electrode; andan outer electrode formed to surround the inner electrodes having theelectrolyte absorption layers all together and including an outerelectrode active material layer and an outer current collector.

Also, a cable-type secondary battery according to an exemplaryembodiment of the present disclosure includes at least two lithium ionsupplying cores comprising an electrolyte; an inner electrode support ofa hollow structure formed to surround the outer surface of each of thelithium ion supplying cores; at least two inner electrodes formed on thesurface of the inner electrode support and arranged in parallel to oneanother, each including an inner electrode active material layer and aninner current collector; a first electrolyte absorption layer formed onthe outer surface of the inner electrode; a separation layer formed tosurround the inner electrodes having the electrolyte absorption layersall together to prevent a short circuit between electrodes; a secondelectrolyte absorption layer formed on the outer surface of theseparation layer; and an outer electrode formed to surround the outersurface of the second electrolyte absorption layer and including anouter electrode active material layer and an outer current collector.

Similarly, in the cable-type secondary battery including the innerelectrode consisted of the plurality of electrodes, the inner electrodemay include an inner electrode active material layer formed to surroundthe outer surface of the inner electrode support and an inner currentcollector formed to surround the outer surface of the inner electrodeactive material layer, or may include an inner current collector formedto surround the outer surface of the inner electrode support and aninner electrode active material layer formed to surround the outersurface of the inner current collector, as described in the foregoing.

Also, besides a structure of including an outer electrode activematerial layer formed to surround the outer surface of the separationlayer and an outer current collector formed to surround the outersurface of the outer electrode active material layer, the outerelectrode may have a structure of including an outer current collectorformed to surround the outer surface of the separation layer and anouter electrode active material layer formed to surround the outersurface of the outer current collector and to come into contact with theseparation layer, or may have a structure of including an outerelectrode active material layer formed to surround the outer surface ofthe separation layer and an outer current collector formed to beincluded inside the outer electrode active material layer and tosurround the outer surface of the separation layer with spacing aparttherefrom.

What is claimed is:
 1. A cable-type secondary battery extendinglongitudinally, comprising: a lithium ion supplying core comprising anelectrolyte; an inner electrode support of a hollow structure formed tosurround an outer surface of the lithium ion supplying core; an innerelectrode formed on a surface of the inner electrode support, andincluding an inner current collector and an inner electrode activematerial layer; a separation layer formed to surround an outer surfaceof the inner electrode to prevent a short circuit between electrodes;and an outer electrode formed to surround an outer surface of theseparation layer, and including an outer electrode active material layerand an outer current collector.
 2. The cable-type secondary batteryaccording to claim 1, wherein the inner electrode support of the hollowstructure is a hollow fiber.
 3. The cable-type secondary batteryaccording to claim 2, wherein the hollow fiber is formed from at leastone selected from the group consisting of polyethylene, polypropylene,polytetrafluoroethylene, polyvinylidenefluoride, polyimide,polyethyleneterephthalate, polyamide-imide, polyester-imide,polyethersulfone, and polysulfone.
 4. The cable-type secondary batteryaccording to claim 1, wherein the inner electrode support of the hollowstructure has a pore on the surface thereof to allow the electrolyte tomove to an inner electrode active material and an outer electrode activematerial.
 5. The cable-type secondary battery according to claim 4,wherein the pore has a diameter in a range of 10 nm to 100 μm.
 6. Thecable-type secondary battery according to claim 1, wherein the innercurrent collector is a wound wire-type current collector, a woundsheet-type current collector, or a metal coating layer.
 7. Thecable-type secondary battery according to claim 1, wherein the innerelectrode includes the inner electrode active material layer formed tosurround the surface of the inner electrode support and the innercurrent collector formed to surround an outer surface of the innerelectrode active material layer, or the inner electrode includes theinner current collector formed to surround the surface of the innerelectrode support and the inner electrode active material layer formedto surround an outer surface of the inner current collector.
 8. Thecable-type secondary battery according to claim 1, wherein the outerelectrode includes the outer electrode active material layer formed tosurround the outer surface of the separation layer and the outer currentcollector formed to surround an outer surface of the outer electrodeactive material layer, the outer electrode includes the outer currentcollector formed to surround the outer surface of the separation layerand the outer electrode active material layer formed to surround anouter surface of the outer current collector, the outer electrodeincludes the outer current collector formed to surround the outersurface of the separation layer and the outer electrode active materiallayer formed to surround the outer surface of the outer currentcollector and to come into contact with the separation layer, or theouter electrode includes the outer electrode active material layerformed to surround the outer surface of the separation layer and theouter current collector formed to be included inside the outer electrodeactive material layer by being covered therein and to surround the outersurface of the separation layer with spacing apart therefrom.
 9. Thecable-type secondary battery according to claim 1, wherein the outercurrent collector is a pipe-type current collector, a wound wire-typecurrent collector, a wound sheet-type current collector, or a mesh-typecurrent collector.
 10. The cable-type secondary battery according toclaim 1, wherein the inner current collector is made of stainless steel;aluminum; nickel; titanium; sintered carbon; copper; stainless steeltreated with carbon, nickel, titanium or silver on a surface thereof; analuminum-cadmium alloy; a non-conductive polymer treated with aconductive material on a surface thereof; or a conductive polymer. 11.The cable-type secondary battery according to claim 10, wherein theconductive material is any one selected from polyacetylene, polyaniline,polypyrrole, polythiophene, polysulfurnitride, indium tin oxide (ITO),silver, palladium, and nickel, or mixtures thereof.
 12. The cable-typesecondary battery according to claim 10, wherein the conductive polymeris a polymer of any one compound selected from polyacetylene,polyaniline, polypyrrole, polythiophene, and polysulfurnitride, ormixtures thereof.
 13. The cable-type secondary battery according toclaim 1, wherein the outer current collector is made of stainless steel;aluminum; nickel; titanium; sintered carbon; copper; stainless steeltreated with carbon, nickel, titanium or silver on a surface thereof; analuminum-cadmium alloy; a non-conductive polymer treated with aconductive material on a surface thereof; a conductive polymer; a metalpaste comprising metal powders of Ni, Al, Au, Ag, Al, Pd/Ag, Cr, Ta, Cu,Ba or ITO; or a carbon paste comprising carbon powders of graphite,carbon black or carbon nanotube.
 14. The cable-type secondary batteryaccording to claim 1, wherein the electrolyte comprises an electrolyteselected from a non-aqueous electrolyte solution using ethylenecarbonate (EC), propylene carbonate (PC), butylene carbonate (BC),vinylene carbonate (VC), diethyl carbonate (DEC), dimethyl carbonate(DMC), ethyl methyl carbonate (EMC), methyl formate (MF),γ-butyrolactone (γ-BL), sulfolane, methyl acetate (MA) or methylpropionate (MP); and a gel-type polymer electrolyte using PEO, PVdF,PMMA, PAN or PVAC; and a solid electrolyte using PEO, polypropyleneoxide (PPO), polyethylene imine (PEI), polyethylene sulphide (PES), orpolyvinyl acetate (PVAc).
 15. The cable-type secondary battery accordingto claim 1, wherein the electrolyte further comprises a lithium salt.16. The cable-type secondary battery according to claim 15, wherein thelithium salt is any one selected from LiCl, LiBr, LiI, LiClO₄, LiBF₄,LiB₁₀Cl₁₀, LiPF₆, LiCF₃SO₃, LiCF₃CO₂, LiAsF₆, LiSbF₆, LiAlCl₄, CH₃SO₃Li,CF₃SO₃Li, (CF₃SO₂)₂NLi, lithium chloroborate, lower aliphatic lithiumcarbonate, and lithium tetraphenylborate, or mixtures thereof.
 17. Thecable-type secondary battery according to claim 1, wherein the innerelectrode is an anode or a cathode, and the outer electrode is a cathodeor an anode, opposite to the inner electrode.
 18. The cable-typesecondary battery according to claim 1, wherein when the inner electrodeis an anode and the outer electrode is a cathode, the inner electrodeactive material layer comprises particles of any one active materialselected from the group consisting of natural graphite, artificialgraphite, or a carbonaceous material; lithium-containing titaniumcomposite oxide (LTO), and metals (Me) including Si, Sn, Li, Zn, Mg, Cd,Ce, Ni and Fe; alloys of the metals (Me); oxides (MeOx) of the metals(Me); and composites of the metals (Me) and carbon, or mixtures thereof,and the outer electrode active material layer comprises particles of anyone active material selected from the group consisting of LiCoO₂,LiNiO₂, LiMn₂O₄, LiCoPO₄, LiFePO₄, LiNiMnCoO₂, andLiNi_(1−x−y−z)Co_(x)M1_(y)M2_(z)O₂ (wherein each of M1 and M2 is,independently, any one selected from the group consisting of Al, Ni, Co,Fe, Mn, V, Cr, Ti, W, Ta, Mg and Mo, and x, y and z are, independently,atomic fractions of elements in an oxide composition, in which 0≦x<0.5,0≦y<0.5, 0≦z<0.5, and x+y+z≦1), or mixtures thereof.
 19. The cable-typesecondary battery according to claim 1, wherein when the inner electrodeis a cathode and the outer electrode is an anode, the inner electrodeactive material layer comprises particles of any one active materialselected from the group consisting of LiCoO₂, LiNiO₂, LiMn₂O₄, LiCoPO₄,LiFePO₄, LiNiMnCoO₂, and LiNi_(1−x−y−z)Co_(x)M1_(y)M2_(z)O₂ (whereineach of M1 and M2 is, independently, any one selected from the groupconsisting of Al, Ni, Co, Fe, Mn, V, Cr, Ti, W, Ta, Mg and Mo, and x, yand z are, independently, atomic fractions of elements in an oxidecomposition, in which 0≦x<0.5, 0≦y<0.5, 0≦z<0.5, and x+y+z≦1), ormixtures thereof, and the outer electrode active material layercomprises particles of any one active material selected from the groupconsisting of natural graphite, artificial graphite, or a carbonaceousmaterial; lithium-containing titanium composite oxide (LTO), and metals(Me) including Si, Sn, Li, Zn, Mg, Cd, Ce, Ni and Fe; alloys of themetals(Me); oxides (MeOx) of the metals(Me); and composites of themetals (Me) and carbon, or mixtures thereof.
 20. The cable-typesecondary battery according to claim 1, wherein the separation layer isan electrolyte layer or a separator.
 21. The cable-type secondarybattery according to claim 20, wherein the electrolyte layer comprisesan electrolyte selected from a gel-type polymer electrolyte using PEO,PVdF, PMMA, PAN or PVAC; and a solid electrolyte using PEO,polypropylene oxide (PPO), polyethylene imine (PEI), polyethylenesulphide (PES), or polyvinyl acetate (PVAc).
 22. The cable-typesecondary battery according to claim 20, wherein the electrolyte layerfurther comprises a lithium salt.
 23. The cable-type secondary batteryaccording to claim 22, wherein the lithium salt is any one selected fromLiCl, LiBr, LiI, LiClO₄, LiBF₄, LiB₁₀Cl₁₀, LiPF₆, LiCF₃SO₃, LiCF₃CO₂,LiAsF₆, LiSbF₆, LiAlCl₄, CH₃SO₃Li, CF₃SO₃Li, (CF₃SO₂)₂NLi, lithiumchloroborate, lower aliphatic lithium carbonate, and lithiumtetraphenylborate, or mixtures thereof.
 24. The cable-type secondarybattery according to claim 20, wherein the separator is a poroussubstrate made of a polyolefin-based polymer selected from the groupconsisting of ethylene homopolymers, propylene homopolymers,ethylene-butene copolymers, ethylene-hexene copolymers, andethylene-methacrylate copolymers; a porous substrate made of a polymerselected from the group consisting of polyesters, polyacetals,polyamides, polycarbonates, polyimides, polyether ether ketones,polyether sulfones, polyphenylene oxides, polyphenylene sulfides andpolyethylene naphthalenes; or a porous substrate made of a mixture ofinorganic particles and a binder polymer.
 25. The cable-type secondarybattery according to claim 1, further comprising: an electrolyteabsorption layer between the inner electrode and the separation layer.26. The cable-type secondary battery according to claim 1, furthercomprising: a first electrolyte absorption layer between the innerelectrode and the separation layer; and a second electrolyte absorptionlayer between the separation layer and the outer electrode.
 27. Thecable-type secondary battery according to claim 1, wherein at least oneof the inner electrode and the outer electrode is a spiral electrode inwhich at least two wires are spirally twisted around each other.
 28. Thecable-type secondary battery according to claim 1, wherein thecable-type secondary battery has a cross section of a circular orpolygonal shape.
 29. A cable-type secondary battery extendinglongitudinally, comprising: at least two lithium ion supplying corescomprising an electrolyte; an inner electrode support of a hollowstructure formed to surround an outer surface of each of the at leasttwo lithium ion supplying cores; at least two inner electrodes formed ona surface of the inner electrode support and arranged in parallel to oneanother, each including an inner current collector and an innerelectrode active material layer; a separation layer formed to surroundouter surfaces of the at least two inner electrodes all together toprevent a short circuit between electrodes; and an outer electrodeformed to surround an outer surface of the separation layer, andincluding an outer electrode active material layer and an outer currentcollector.
 30. The cable-type secondary battery according to claim 29,further comprising: an electrolyte absorption layer on the outersurfaces of the at least two inner electrodes.
 31. The cable-typesecondary battery according to claim 29, further comprising: a firstelectrolyte absorption layer on the outer surfaces of the at least twoinner electrodes; and a second electrolyte absorption layer on the outersurface of the separation layer.
 32. The cable-type secondary batteryaccording to claim 29, wherein at least one of the at least two innerelectrodes and the outer electrode is a spiral electrode in which atleast two wires are spirally twisted around each other.
 33. A cable-typesecondary battery extending longitudinally, comprising: at least twolithium ion supplying cores comprising an electrolyte; an innerelectrode support of a hollow structure formed to surround an outersurface of each of the at least two lithium ion supplying cores; atleast two inner electrode-separation layer assemblies formed on asurface of the inner electrode support and arranged in parallel to oneanother, each including an inner electrode having an inner currentcollector and an inner electrode active material layer and a separationlayer formed to surround an outer surface of the inner electrode; and anouter electrode formed to surround outer surfaces of the at least twoinner electrode-separation layer assemblies all together, and includingan outer electrode active material layer and an outer current collector.34. A cable-type secondary battery extending longitudinally, comprising:at least two lithium ion supplying cores comprising an electrolyte; aninner electrode support of a hollow structure formed to surround anouter surface of each of the at least two lithium ion supplying cores;at least two inner electrodes formed on a surface of the inner electrodesupport and arranged in parallel to one another, each including an innerelectrode active material layer and an inner current collector; anelectrolyte absorption layer formed on an outer surface of each of theat least two inner electrodes; a separation layer formed to surround theat least two inner electrodes having the electrolyte absorption layersall together to prevent a short circuit between electrodes; and an outerelectrode formed to surround an outer surface of the separation layerall together, and including an outer electrode active material layer andan outer current collector.
 35. A cable-type secondary battery extendinglongitudinally, comprising: at least two lithium ion supplying corescomprising an electrolyte; an inner electrode support of a hollowstructure formed to surround an outer surface of each of the at leasttwo lithium ion supplying cores; at least two inner electrodes formed ona surface of the inner electrode support and arranged in parallel to oneanother, each including an inner electrode active material layer and aninner current collector; at least two electrolyte absorption layers eachformed on an outer surface of the at least two inner electrodes; and anouter electrode formed to surround the at least two inner electrodeshaving the at least two electrolyte absorption layers all together, andincluding an outer electrode active material layer and an outer currentcollector.
 36. A cable-type secondary battery extending longitudinally,comprising: at least two lithium ion supplying cores comprising anelectrolyte; an inner electrode support of a hollow structure formed tosurround an outer surface of each of the at least two lithium ionsupplying cores; at least two inner electrodes formed on a surface ofthe inner electrode support and arranged in parallel to one another,each including an inner electrode active material layer and an innercurrent collector; a first electrolyte absorption layer formed on anouter surface of each of the at least two inner electrodes; a separationlayer formed to surround the at least two inner electrodes having thefirst electrolyte absorption layers all together to prevent a shortcircuit between electrodes; a second electrolyte absorption layer formedon an outer surface of the separation layer; and an outer electrodeformed to surround an outer surface of the second electrolyte absorptionlayer, and including an outer electrode active material layer and anouter current collector.